Check if call result is undefined

Question

how can I check if the result to call a JavaScript function is undefined?

I tried with

if( s.getNode(id1) != js.undefined) 

but fastOptJS say:

scala.scalajs.js.Dynamic and scala.scalajs.js.UndefOr[Nothing] are unrelated: they will most likely always compare unequal

TIA

Answer 1

This is Scala's type system being a bit "too" helpful.

To compare against undefined, you can use js.isUndefined:

if (!js.isUndefined(s.getNode(id1)))